The following invention relates to a brushless electromechanical machine for converting electrical energy into mechanical motion and vice-versa. More specifically, the invention relates to an electric motor/generator having self-starting capabilities, high torque and increased efficiency.
Electric motors employing brushes are characterized by low efficiency and require elaborate starter mechanisms. Recently, a type of brushless motor has been developed which employs an electromagnet having a stator comprised of a plurality of toroidal pole pieces. The pole pieces each have a narrow gap to permit the passage of a disk shaped rotor. The rotor includes a plurality of permanent magnet members spaced about the periphery of the disk. As the permanent magnet members pass through the gap in the stator poles, the magnetic circuit is completed. With appropriate switching circuitry, this combination can be made to function as a brushless electric motor. An example of such construction is shown in the Porter U.S. Pat. No. 5,179,307.
In the Porter motor, the permanent magnets on the rotor are widely spaced apart. The rotor is a disk having permanent magnet members situated about its periphery and spaced 36.degree. apart. The driving circuitry is triggered by combinations of light emitting diodes and photosensitive transistors arranged on opposite sides of the rotor disk. Apertures in the rotor disk permit light from and LED to fall on a photosensitive transistor at appropriate points in the rotation of the rotor disk. This causes the driving current to cause current to flow in the coil.
A problem with the motor of the '307 patent is that the permanent magnets are spaced too far apart about the periphery of the rotor disk for the machine to operate efficiently. This wide spacing of permanent magnet members would require a large mass rotor operating as a flywheel with enough energy stored in the rotor to provide considerable rotational momentum. A large mass rotor, however, would be impossible to start without some type of auxiliary starter mechanism. Additionally, this motor cannot easily reverse its direction.